John - be a good idea if you greased that paddle back up [use vaseline] - meant to be that way to seal the chamber - the outlet you plugged is prolly there for a good reason, like to allow the vacuum to release when it gets to the end of the stroke
see the wiperman!! good luck w/ it and the truck, and welcome to the garage - don't hesitate to ask about anything here, be someone along who knows more about it than I
Bill